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<meta name="description" content="A continuously operating ForceDirectedLayout lets the user push and pull nodes around."/> 
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<title>Interactive Force Directed Layout</title>
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          <h1 class="mb-0 p-1 ">GoJS</h1>
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    <!-- Start of GoJS sample code -->
    
    <script src="../release/go.js"></script>
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    <script id="code">
    // This variation on ForceDirectedLayout does not move any selected Nodes
    // but does move all other nodes (vertexes).
    function ContinuousForceDirectedLayout() {
      go.ForceDirectedLayout.call(this);
      this._isObserving = false;
    }
    go.Diagram.inherit(ContinuousForceDirectedLayout, go.ForceDirectedLayout);

    ContinuousForceDirectedLayout.prototype.isFixed = function(v) {
      return v.node.isSelected;
    }

    // optimization: reuse the ForceDirectedNetwork rather than re-create it each time
    ContinuousForceDirectedLayout.prototype.doLayout = function(coll) {
      if (!this._isObserving) {
        this._isObserving = true;
        // cacheing the network means we need to recreate it if nodes or links have been added or removed or relinked,
        // so we need to track structural model changes to discard the saved network.
        var lay = this;
        this.diagram.addModelChangedListener(function(e) {
          // modelChanges include a few cases that we don't actually care about, such as
          // "nodeCategory" or "linkToPortId", but we'll go ahead and recreate the network anyway.
          // Also clear the network when replacing the model.
          if (e.modelChange !== "" ||
            (e.change === go.ChangedEvent.Transaction && e.propertyName === "StartingFirstTransaction")) {
            lay.network = null;
          }
        });
      }
      var net = this.network;
      if (net === null) {  // the first time, just create the network as normal
        this.network = net = this.makeNetwork(coll);
      } else {  // but on reuse we need to update the LayoutVertex.bounds for selected nodes
        this.diagram.nodes.each(function(n) {
          var v = net.findVertex(n);
          if (v !== null) v.bounds = n.actualBounds;
        });
      }
      // now perform the normal layout
      go.ForceDirectedLayout.prototype.doLayout.call(this, coll);
      // doLayout normally discards the LayoutNetwork by setting Layout.network to null;
      // here we remember it for next time
      this.network = net;
    }
    // end ContinuousForceDirectedLayout


    function init() {
      var $ = go.GraphObject.make;  // for conciseness in defining templates

      myDiagram =
        $(go.Diagram, "myDiagramDiv",  // must name or refer to the DIV HTML element
          {
            initialAutoScale: go.Diagram.Uniform,  // an initial automatic zoom-to-fit
            contentAlignment: go.Spot.Center,  // align document to the center of the viewport
            layout:
              $(ContinuousForceDirectedLayout,  // automatically spread nodes apart while dragging
                { defaultSpringLength: 30, defaultElectricalCharge: 100 }),
            // do an extra layout at the end of a move
            "SelectionMoved": function(e) { e.diagram.layout.invalidateLayout(); }
          });

      // dragging a node invalidates the Diagram.layout, causing a layout during the drag
      myDiagram.toolManager.draggingTool.doMouseMove = function() {
        go.DraggingTool.prototype.doMouseMove.call(this);
        if (this.isActive) { this.diagram.layout.invalidateLayout(); }
      }

      // define each Node's appearance
      myDiagram.nodeTemplate =
        $(go.Node, "Auto",  // the whole node panel
          // define the node's outer shape, which will surround the TextBlock
          $(go.Shape, "Circle",
            { fill: "CornflowerBlue", stroke: "black", spot1: new go.Spot(0, 0, 5, 5), spot2: new go.Spot(1, 1, -5, -5) }),
          $(go.TextBlock,
            { font: "bold 10pt helvetica, bold arial, sans-serif", textAlign: "center", maxSize: new go.Size(100, NaN) },
            new go.Binding("text", "text"))
        );
      // the rest of this app is the same as samples/conceptMap.html

      // replace the default Link template in the linkTemplateMap
      myDiagram.linkTemplate =
        $(go.Link,  // the whole link panel
          $(go.Shape,  // the link shape
            { stroke: "black" }),
          $(go.Shape,  // the arrowhead
            { toArrow: "standard", stroke: null }),
          $(go.Panel, "Auto",
            $(go.Shape,  // the label background, which becomes transparent around the edges
              {
                fill: $(go.Brush, "Radial", { 0: "rgb(240, 240, 240)", 0.3: "rgb(240, 240, 240)", 1: "rgba(240, 240, 240, 0)" }),
                stroke: null
              }),
            $(go.TextBlock,  // the label text
              {
                textAlign: "center",
                font: "10pt helvetica, arial, sans-serif",
                stroke: "#555555",
                margin: 4
              },
              new go.Binding("text", "text"))
          )
        );

      // create the model for the concept map
      var nodeDataArray = [
        { key: 1, text: "Concept Maps" },
        { key: 2, text: "Organized Knowledge" },
        { key: 3, text: "Context Dependent" },
        { key: 4, text: "Concepts" },
        { key: 5, text: "Propositions" },
        { key: 6, text: "Associated Feelings or Affect" },
        { key: 7, text: "Perceived Regularities" },
        { key: 8, text: "Labeled" },
        { key: 9, text: "Hierarchically Structured" },
        { key: 10, text: "Effective Teaching" },
        { key: 11, text: "Crosslinks" },
        { key: 12, text: "Effective Learning" },
        { key: 13, text: "Events (Happenings)" },
        { key: 14, text: "Objects (Things)" },
        { key: 15, text: "Symbols" },
        { key: 16, text: "Words" },
        { key: 17, text: "Creativity" },
        { key: 18, text: "Interrelationships" },
        { key: 19, text: "Infants" },
        { key: 20, text: "Different Map Segments" }
      ];
      var linkDataArray = [
        { from: 1, to: 2, text: "represent" },
        { from: 2, to: 3, text: "is" },
        { from: 2, to: 4, text: "is" },
        { from: 2, to: 5, text: "is" },
        { from: 2, to: 6, text: "includes" },
        { from: 2, to: 10, text: "necessary\nfor" },
        { from: 2, to: 12, text: "necessary\nfor" },
        { from: 4, to: 5, text: "combine\nto form" },
        { from: 4, to: 6, text: "include" },
        { from: 4, to: 7, text: "are" },
        { from: 4, to: 8, text: "are" },
        { from: 4, to: 9, text: "are" },
        { from: 5, to: 9, text: "are" },
        { from: 5, to: 11, text: "may be" },
        { from: 7, to: 13, text: "in" },
        { from: 7, to: 14, text: "in" },
        { from: 7, to: 19, text: "begin\nwith" },
        { from: 8, to: 15, text: "with" },
        { from: 8, to: 16, text: "with" },
        { from: 9, to: 17, text: "aids" },
        { from: 11, to: 18, text: "show" },
        { from: 12, to: 19, text: "begins\nwith" },
        { from: 17, to: 18, text: "needed\nto see" },
        { from: 18, to: 20, text: "between" }
      ];
      myDiagram.model = new go.GraphLinksModel(nodeDataArray, linkDataArray);
    }

    function reload() {
      //myDiagram.layout.network = null;
      var text = myDiagram.model.toJson();
      myDiagram.model = go.Model.fromJson(text);
      //myDiagram.layout =
      //  go.GraphObject.make(ContinuousForceDirectedLayout,  // automatically spread nodes apart while dragging
      //    { defaultSpringLength: 30, defaultElectricalCharge: 100 });
    }
    window.addEventListener('DOMContentLoaded', init);
  </script>

<div id="sample">
  <div id="myDiagramDiv" style="background-color: whitesmoke; border: solid 1px black; width: 100%; height: 700px"></div>
  <p>
    As you drag a node around, the custom <a>ForceDirectedLayout</a> operates continuously, causing other nodes to be pushed
    aside or pulled along.
  </p>
  <p>
    The graph is exactly the same as the <a href="conceptMap.html">Concept Map</a> sample.
    But the node template is different, and the layout is different.
  </p>
</div>
    </div>
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